Experimental approaches to the treatment of meningeal leukemia and other meningeal and non-meningeal CNS neoplasms are explored. A unique subhuman primate model which allows sterile, repetitive access to the cerebrospinal fluid is utilized to study the CNS pharmacokinetics of various intrathecally and intravenously administered chemotherapeutic agents; to evaluate the neurotoxicities attendant upon various chemotherapeutic and radiotherapeutic treatments; and to evaluate and screen, in a preclinical setting, newer CNS treatment modalities and drug schedules. Information gained from studies with this model is then applied to the design of clinical protocols used to treat patients with meningeal and non-meningeal malignancies.